Loudspeakers generally comprise a frame, a motor structure, a diaphragm, a lower suspension or spider and a surround or upper suspension. In one type of speaker, the motor structure includes a permanent magnet sandwiched between a top plate and a back plate, with a pole piece having a through bore centrally mounted on the back plate so that both the top plate and magnet are concentrically disposed about the pole piece. A magnetic gap is formed between the pole piece and top plate within which a voice coil is axially movable. Preferably, the voice coil consists of a hollow, cylindrical-shaped former having an inner surface and an outer surface which mounts a winding of wire.
The voice coil in speakers of the type described above is mounted within the magnetic gap by the upper and lower suspensions and the diaphragm. One end of the diaphragm is connected to the upper suspension, which, in turn, is mounted to the upper end of the frame. The lower suspension is connected at one end to the frame at a point between its upper and lower ends. The free ends of the diaphragm and lower suspension are mounted to the outer surface of the former of the voice coil and support it for axial movement within the magnetic gap. In the course of operation of such speakers, electrical energy is supplied to the voice coil causing it to axially move within the magnetic gap. The voice coil, diaphragm, upper suspension, lower suspension, and dust cap, if present, collectively form an assembly which reciprocates as a unit with the excursion of the voice coil.
Speakers may be mounted within the interior of an enclosure having a front panel formed with an opening such that a forward-facing surface of the diaphragm aligns with the opening. Speaker enclosures may help prevent sound waves produced by the rearward-facing surface of the diaphragm from interacting with those emanating from its forward-facing surface, and help ensure that such sound waves arrive at a listener's ear at substantially the same time.
Speaker systems comprising a loudspeaker and an enclosure may be equipped with light sources such as LEDs. Typically, the LEDs are located in the area of the opening in the front panel of the enclosure, such as in or on a grill placed over such opening, or along a portion of the front panel of the enclosure. This construction may be suitable for indoor use. However, in harsher environments such as outdoor and marine applications where exposure to water, moisture, dirt and other potentially harmful elements is common, mounting LEDs as noted above can damage or render them inoperative.